The field of the invention relates generally to battery powered electronic devices, and more specifically to intrinsically safe electronic devices such as industrial radio devices.
When electronic devices are operated in hazardous environments, such as those having explosive gas atmospheres, intrinsic safety of the devices is of concern. Intrinsic safety standards are codifed, for example, in IEC 60079-0. When such instrinsic safety standards are successfully implemented, it can be ensured that the available electrical and thermal energy associated with an electronic device remains sufficiently low to prevent ignition in a hazardous atmosphere that is otherwise susceptible to it. This is typically accomplished by ensuring that electronic devices used in hazardous areas operate only with low voltages and currents, with appropriate safety and isolation barriers to ensure safe operation of the device in hazardous environments.
Self contained, battery powered devices have been developed with instrinsic safety features in normal use. Routine maintenance procedures for such devices, however, can compromise well designed intrinsic safety features of the device if the maintenance procedures are performed in the hazardous environment. For example, if one attempts to access the batteries of the device after removing a protective cover, and then disconnect or connect the batteries of the device while remaining in a hazardous environment, small sparking may result between a battery and the battery retaining clip as the circuit is effectively made or broken by inserting or removing the batteries. In a hazardous environment, any sparking is simply unacceptable.
To address sparking issues associated with batteries of an electronic device, some known electronic devices include a battery harness with a plug type connector engaging a socket type connector of the main circuit board in the device. To replace the batteries in devices of this type, the plug connector must first be removed from the socket connector to de-energize the circuit including the harness. Next, the battery harness must be removed from the device, and the batteries can then be removed from the harness and be replaced. While such features can and do provide an additional degree of safety when properly used, it is possible that they may be mis-used in a manner in which the safety features are defeated. For example, one may remove the harness from the device and attempt to remove the batteries from the harness without first unplugging the harness from the device, and sparking can still result.